55 lines
2.3 KiB
Markdown
55 lines
2.3 KiB
Markdown
# Bridge contract
|
|
|
|
Return: 0 = accepted, 1..10 = am_error values in atom_mb.h.
|
|
256 = invalid/stale handle, 257 = pool full, 258 = insufficient/null buffer,
|
|
259 = unknown command. Always inspect return codes. A rejected call is not a
|
|
completed Modbus request.
|
|
|
|
Commands: 1 Open, 2 Close, 3 Enable, 4 Disable, 5 Tick, 6 Submit,
|
|
7 CopyRead, 8 Reconnect, 9 Configure, 10 Acknowledge,
|
|
11 Set request timeout (responseTimeoutMs only; permitted while not busy).
|
|
Configure only while disabled; all three timeouts must be nonzero.
|
|
Open receives an IPv4 DWORD in human octet order: 16#C0A80132 = 192.168.1.50.
|
|
Open returns its handle in status[0], NOT in the function return value.
|
|
Close returns status[0]=0; old handles fail even when their slot is reused.
|
|
Capacity values count WORD/UDINT elements, not bytes. Pass separate buffers.
|
|
CopyRead copies `quantity` WORDs; coils/discretes are unpacked WORD 0/1.
|
|
|
|
| Status index | Meaning |
|
|
|---|---|
|
|
| 0 | Handle |
|
|
| 1 | State: 0 Disabled, 1 Retry, 2 Connecting, 3 Ready, 4 Sending, 5 Receiving |
|
|
| 2 | Busy |
|
|
| 3 | Done |
|
|
| 4 | Error |
|
|
| 5 | Latest transaction result |
|
|
| 6 | Last failure, retained after success |
|
|
| 7 | OS socket error |
|
|
| 8 | Modbus exception |
|
|
| 9 | Write outcome uncertain |
|
|
| 10 | Connection attempts |
|
|
| 11 | Attempts after first attempt |
|
|
| 12 | Completed successful requests |
|
|
| 13 | Failed requests |
|
|
| 14 | Has successful transaction |
|
|
| 15 | Last success timestamp, low 32 bits |
|
|
| 16 | Last success timestamp, high 32 bits |
|
|
| 17 | Quantity of latest request |
|
|
| 18 | Function code |
|
|
| 19 | Unit ID |
|
|
| 20 | Enabled |
|
|
| 21 | Connect timeout milliseconds |
|
|
| 22 | Whole-request timeout milliseconds |
|
|
| 23 | Retry delay milliseconds |
|
|
|
|
The PLC wrapper consumes Done/Error then Acknowledge before submitting a new
|
|
request. For Done reads, call CopyRead BEFORE Acknowledge. Completed read data
|
|
is retained internally but CopyRead requires Done. For writes, do not replay
|
|
an uncertain result without an application decision.
|
|
|
|
All calls to the entire bridge pool must originate from ONE IEC task. Contexts
|
|
and the pool are not thread-safe. Handles must not be RETAIN/PERSISTENT. Closing
|
|
on program disposal and invalidating on application reset/download remain PLC
|
|
wrapper responsibilities. Component unload cleanup alone does not cover an IEC
|
|
application stop or download.
|